OXNARD, Calif. -- Dallas Cowboys running back Ezekiel Elliott has been suspended six games by the NFL for violating the personal conduct policy, a source told ESPN's Adam Schefter.

The suspension comes as a result of an investigation that started more than a year ago after an ex-girlfriend accused Elliott of domestic violence in Columbus, Ohio. The Columbus City Attorney's office announced in September that it would not pursue charges against Elliott because of "conflicting and inconsistent information," but the NFL can penalize a player even without legal charges.

Elliott is expected to appeal the suspension, league sources told Schefter.

Elliott has three business days to file notice of appeal, and a hearing must be scheduled within 10 days of receipt of the notice, according to Article 46 of the collective bargaining agreement, which governs appeal of commissioner discipline.

Commissioner Roger Goodell or his designee, usually former NFL executive Harold Henderson, would hear the appeal.

Legal authorities concluded that Elliott's accuser was not credible and rejected charging him. Several witnesses, according to sources close to the case, heard the woman yell at Elliott that she would "ruin his career" when she was unhappy that they would not continue their relationship.

The league's suspension of Elliott differs from the 2014 ban of then-Baltimore Ravens running back Ray Rice, who was prosecuted and agreed to a plea resolution after a full investigation by legal authorities.

The NFL believes it has investigated Elliott's case thoughtfully, thoroughly and extensively and that Elliott violated the personal conduct policy. The league went through text messages and retained medical and legal experts to help Goodell make his decision.

Before disciplining Elliott, the NFL considered the domestic violence allegations from February and July 2016, as well as the St. Patrick's Day incident in which he pulled down a woman's shirt, though that did not factor into the league's decision on discipline.

Also, before the team left for training camp, Elliott was allegedly involved in an incident at a Dallas bar that left a man with a nose injury. Dallas police have suspended the investigation because they could not contact the victim and no witnesses came forward.

Cowboys owner and general manager Jerry Jones has defended Elliott throughout the NFL's investigation.

"I have reviewed everything, and there is absolutely nothing -- not one thing -- that had anything to do with domestic violence," Jones said at the Cowboys' opening news conference at training camp in Oxnard.

The NFL disagreed. Elliott is the third Cowboys player who will miss time this season because of a suspension. Defensive end Randy Gregory has been suspended for the season after multiple violations of the substance-abuse policy. Defensive end David Irving has been suspended the first four games for violating the performance-enhancing drug policy.

There are people in and around the Cowboys organization who are growing increasingly concerned about Elliott's lifestyle and choices. Elliott has become known for frequenting Dallas nightclubs, and there are concerns about the way he has conducted himself, sources close to the situation told Schefter.

Now, his young career is at something of a crossroads. Elliott will not be allowed into the Cowboys' training complex from the first week of the regular season until the suspension is complete. He will be left on his own, where he either can work with the services available to him or can squander the time away, which would raise further questions about his behavior.

Elliott, the fourth overall pick in the 2016 draft, led the NFL in rushing last season with 1,631 yards on 322 carries. He scored 15 rushing touchdowns. He also caught 32 passes for 363 yards and one touchdown and was named to the Pro Bowl.

With Elliott out, the Cowboys will turn to Darren McFadden, Rod Smith and Alfred Morris as their running backs. The team signed veteran Ronnie Hillman at the end of July, but coach Jason Garrett said the addition had nothing to do with Elliott's potential suspension.

McFadden finished fourth in the NFL in rushing in 2015 with 1,089 yards despite not taking over until the seventh game of the season. He was limited to 24 carries last year because of a broken elbow. Morris has three 1,000-yard seasons to his credit but had 69 carries for 243 yards and two touchdowns in limited work last season. Smith has been taking turns as the third tailback in the early part of training camp.

The suspension will be costly for Elliott. In addition to losing his base-salary pay, the guarantees in Elliott's $24.956 million deal will be voided. He received a signing bonus of $16.350 million and got the final deferred installment of the bonus in March. Once he misses games, he will have to pay back some of the signing-bonus money. For each game missed, Elliott will have to repay about $240,000.

Elliott's base salaries for 2017 to 2019 are worth $1.584 million, $2.718 million and $3.853 million, respectively. He would still receive those amounts for as long as he is on the roster, but they would no longer be guaranteed if he suffered an injury that would end his career.